-LRB- CNN -RRB- -- Watch out ! Lock up your loved ones ! Another bloated , over-produced , high-concept monstrosity has escaped from the labs at Dreamworks Animation , and it 's out to devour your kids .

Susan , aka `` Ginormica , '' has to save the world in `` Monsters vs. Aliens . ''

But do n't be too alarmed . `` Monsters vs. Aliens '' is relatively harmless -- a toothless satire with a knee-jerk feminist theme and a sorry excuse for a plot .

That sounds harsh , I know . Who does n't want to see a 50-foot woman careening through San Francisco on skates that turn out to be automobiles -- the ultimate demolition roller derby ?

But think about that , just for a second . Roller skates work because they have fixed wheels . Try it with motorcars and you wo n't get very far .

Is that too picky ? Perhaps , but you would n't find Pixar playing so fast and loose with the laws of physics , and that kind of inattention to detail is typical of the lackadaisical storytelling here and in other Dreamworks animated features . -LRB- The talent pool for this one includes the directors of `` Shrek 2 '' and `` Shark Tale '' and the writers of `` Kung Fu Panda '' and `` The Rocker , '' incidentally . -RRB- High concepts , top-notch voice talent and scattershot pop cultural references are no compensation for a coherent script .

The XXXL lady in question -- dubbed `` Ginormica '' by her U.S. military guards -- starts out plain and petite Susan Murphy -LRB- voiced by Reese Witherspoon -RRB- , until a meteorite hits her just minutes before she 's supposed to tie the knot with unctuous chauvinist Derek -LRB- Paul Rudd -RRB- .

Her rapid growth spurt saves her from that particular fate worse than death , even if at first glance her new roommates do n't look like much of an improvement .

There 's Dr. Cockroach -LRB- Hugh Laurie -RRB- , a mad scientist who semi-advertently mutated with a bug ; B.O.B. -LRB- Seth Rogen -RRB- an amorphous blue jelly-like blob who gets on just fine without a brain ; Missing Link -LRB- Will Arnett -RRB- , a gung-ho amphibian who 's all mouth ; and a giant dust mite called Insectosaurus who is n't voiced by anyone because he does n't have anything to say .

Sci-fi fans will have fun counting off the references to myriad classics -- `` Close Encounters of the Third Kind , '' `` Invaders from Mars , '' `` The Fly , '' `` The Creature from the Black Lagoon , '' `` The Blob , '' `` Mothra '' and `` Attack of the 50-Foot Woman , '' for starters -- and noting a few clever bits and pieces -LRB- Kiefer Sutherland , as General W.R. Monger , riffs on George C. Scott in `` Dr. Strangelove '' -RRB- .

The trouble is , once the introductions are over , the filmmakers can only launch their desperately limp plot : The White House turns to these monstrous superheroes to save the planet from evil Gallaxhar -LRB- Rainn Wilson -RRB- , a squidlike creature with four eyes and twice as many legs , and a one-eyed tin robot to do his dirty work for him .

Ginormica gets a kick-butt finale , and is a much stronger character -- in any number of ways -- than the movie 's president . -LRB- In a genuinely witty casting touch he 's voiced by Stephen Colbert . -RRB-

That may be good politics or at least a sound marketing decision from the studio 's perspective -- it 's been awhile since a family animated feature produced a genuinely strong female character -LRB- unless you count `` Coraline , '' which was way too scary for my family -RRB- -- but Susan 's self-esteem is an awfully long time coming . iReport.com : What do you think of ` Monsters vs. Aliens ' ?

-LRB- Bizarrely -- and maybe it 's just my imagination -- Gallaxhar bears a passing resemblance to President Obama . I wonder ... would that make Susan/Ginormica a surrogate for Sarah Palin or Hillary Clinton ? -RRB-

Visually , too , `` Monsters vs Aliens '' is undistinguished , although its shortcomings may be disguised if you seek out the 3-D version . Funny how 3-D movies tend to produce two-dimensional characters , with `` Coraline '' again the exception to the rule .

Jocular and unpretentiously trashy , `` Monsters vs. Aliens '' should be a lot of fun -- and it is , in places . But the truth is it 's as hung up on itself as Susan 's preening fiance . Hand on heart , I had a better time at `` Space Chimps . ''

`` Monsters vs. Aliens '' runs 94 minutes and is rated PG . For Entertainment Weekly 's take , click here .

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`` Monsters vs. Aliens '' about Earth-born `` monsters '' taking on megalomaniacal alien

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Film 's main character is almost 50-foot woman voiced by Reese Witherspoon

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`` Monsters '' has great talent but no script to speak of , says Tom Charity